1. Field of the invention
The present invention relates to a disk kind identifying method and a disk apparatus. More specifically, the present invention relates to a disk kind identifying method and a disk apparatus which identifies a DVD-RW or a DVD+RW and executes recording and reproducing depending upon a kind of an identified disk.
2. Description of the prior art
An example of such kind of a conventional disk apparatus is disclosed in a Japanese Patent Laying-open No. 9-198779 (G11B 19/12, G11B 7/00) laid-open on Jul. 31, 1997. The disk apparatus of the prior art detects a presence or absence of a wobble signal when a disk is rotated at a predetermined number of rotations. In a case the wobble signal is absent, the disk is determined whether the CD or the DVD in response to outputs (lock signals) from different PLL circuits each of which is locked with reproducing signals of the CD or the DVD by switching between rotation control circuits for rough servo and precise servo. On the other hand, in a case the wobble signal is present, it is determined whether the disk is the CD−R or the DVD−R on the basis of a frequency of the wobble signal. In the disk identifying apparatus, after identifying the disk, the rotation control circuit corresponding to the CD (CD−R) or the DVD (DVD−R) is selected.
In the prior art, the frequency of the wobble signal is detected, and therefore, a large-scale digital circuit for measuring the frequency is provided. However, since the CD (CD−R) and the DVD (DVD−R) are different from each other in track pitch and reflectivity, in the disk identifying apparatus of the prior art which identifies the CD (CD−R) or the DVD (DVD−R) and selects a rotation control circuit corresponding to each of them, such the digital circuit for detecting the frequency of the wobble signal is unnecessary. That is, it was possible to easily identify the CD (CD−R) or the DVD (DVD−R) on the basis of a focusing signal.
Furthermore, strictly speaking, in a case of identifying the CD or the DVD, or in a case of identifying the CD−R or the DVD−R, since they are different in track pitch and etc. described above, change of a wavelength of a laser beam is required, and therefore, in the above-described prior art, it is impossible to accurately identify the disk. In addition, the above-described prior art is for a media different in track pitch, and does not correspond to the disk such as DVD+R, DVD-R and etc. which are the same in track pitch and reflectivity.